1. Technical Field
The present invention relates to a liquid ejecting apparatus having a liquid ejection head configured to eject liquid supplied from a liquid reservoir unit having liquid stored therein from nozzle openings.
2. Related Art
As a liquid ejecting apparatus configured to eject liquid on ejected media, for example, an ink jet recording apparatus configured to perform printing on an ink-ejected medium such as a paper or a recording sheet by causing ink to be ejected as liquid is known.
There has also been proposed an ink jet recording apparatus including a drum-type platen that causes an ink-ejected medium to be wound therearound and ink jet recording heads provided around the platen, and in which printing is performed on the ink-ejected medium by the ink jet recording heads (see JP-A-2009-184264, for example).
In contrast, there has been proposed an ink jet recording apparatus configured to circulate ink by returning ink supplied from a reservoir unit having ink stored therein to the reservoir unit (see JP-A-2009-23289, for example).
With an ink jet recording apparatus of this type, precipitation of an ink component can be restrained and uniformization of ink temperature is achieved by circulating the ink. Also, by circulating the ink, air bubbles in the ink jet recording head can be returned to the reservoir unit, thereby achieving an advantage of being superior in air-bubble discharging performance.
However, if an ink jet recording head having a plurality of nozzle row groups including one or more nozzle rows and a plurality of circulation channels communicating with the nozzle row groups respectively is arranged at an angle which results in the circulating channels being positioned at different levels in the vertical direction as in JP-A-2009-184264, there arises a difference in waterhead pressure due to the difference in level of the circulation channels. Consequently, the supply pressure of ink fluctuates from one nozzle row group to another, whereby fluctuations in ink discharging characteristics due to the fluctuations in supply characteristics may disadvantageously result.
If the plurality of ink jet recording heads are arranged at different positions in the vertical direction, there also arises a difference in waterhead pressure among the plurality of ink jet recording heads, so that fluctuations in ink discharging characteristics may disadvantageously occur among the ink jet recording heads.
Such problems exist not only in an ink jet recording apparatus, but also in a liquid ejecting apparatus which ejects liquid other than ink.